At present, many advanced and matured techniques, like OFDM modulation and MIMO antenna, are applied in wireless technology development. With the incoming completion of standardization of these new wireless techniques, the performance of a wireless network in terms of throughput and delay has been greatly improved. In a new wireless system, the LTE (Long Term Evolution) network technique is a representative wireless technique based on OFDM and MIMO. It is currently supported by many operators and providers.
An LTE system supports Multi-cast data transmission in addition to the conventional Uni-cast data transmission. Specifically, FIG. 1 shows the composition of an LTE physical-layer frame. In an LTE system, a 10 ms-long transmission frame 101 is divided into 10 subframes 102 at an interval of 1 ms. Here, some of the subframes can be defined by the system as subframes for Multi-cast transmission. In the subframes supporting Multi-cast transmission, Uni-cast data can be mixed and transmitted in a specified format with TDM multiplexing.
In an OFDM system, when all cells share a single frequency for transmission, in the edge of each cell, signal enhancement can be gained with subframes in Multi-cast transmission for the same transmission content. Therefore, a system in which multimedia broadcast information is transmitted in Multi-cast service and the cells share a single frequency for transmission is called MBSFN (Multimedia Broadcast Single-frequency network).
In the MBSFN, a user equipment (UE) can obtain MBSFN configuration information of a cell where the UE is located, i.e., specific subframe information on configuration of data transmission in MBSFN mode (subframe number), by reading a broadcast control channel (BCCH). With the system information transmitted via the BCCH, UE can also obtain the MBSFN information on neighboring cells relative to the serving cell. At present, the LTE standard specification has already supported such broadcast of the neighboring cell MBSFN configuration information. In the broadcast information, however, some problem exists in message definition, which tends to make the UE unable to accurately learn about MBSFN configurations of the neighboring cells, and thus unable to accurately obtain a strategy for measuring the signals from the neighboring cells. The present invention is made in view of the above problem.
The LTE system is divided into two types of Frame type 1 (MD) and Frame type 2 (TDD) according to the schemes of TDD and FDD. For these two frames structures, SCH (synchronization channel) is transmitted via the zeroth and the fifth subframes in Frame Type 1, and the SCH is transmitted via the first and the sixth subframes in Frame Type 2. If the MBSFN information of one of the neighboring cells can not be correctly transmitted to the UE in the serving cell, the UE is likely to assume all of the subframes, except the one for SCH transmission, are MBSFN subframes in the neighboring cell. Therefore, the UE can perform signal strength measurement only on the subframes for SCH transmission, which results in a degradation of the performance of signal strength measurement for the neighboring cell The present invention can avoid the above disadvantage by perfecting message definition in the current standard.